Condenser



p 6, 1950 B. B. MlNNlUM ETAL 2,523,664

CONDENSER Filed July 6, 1946 2 Sheets-Sheet 1 B. B. MINNIUM ET CONDENSER Sept. 26, 1950 Filed July 6, 1946 2 Sheets-Sheet 2 Patented Sept 26, 1950 CONDENSER Byron B. Minnium and Marcius Lee Crooks, Erie, Pa., aslignors to Eric Resistor Corporation, Erie, Pa., a corporation of Pennsylvania Application July 6, 1946, Serial No. 681,656

2 Claims. 1

This invention is intended to provide a condenser in which the terminal connections are made by sheets of spring metal arranged between the sheets of dielectric and having fingers or serrations projecting beyond the dielectric and resiliently engaging the condenser terminals. In one form of the invention the sheets of spring metal serve as the conducting elements or plates of the condenser. In another form the conducting plates of the condenser are metallic coatings on the dielectric and the sheets of spring metal are arranged on the metallic coatings and serve to make the terminal connections. Further objects and advantages appear in the specification and claims.

In the drawing, Fig. 1 is a sectional view of a mica condenser; Fig. 2 is an exploded view; Fig. 3 is a sectional view on line 3--3 of Fig. 4; Fig. 4 is a plan view of the spring metal sheet making contact with the center terminal of the condenser; Fig. 5 is a sectional view on line 5-5 of Fig. 6; Fig. 6 is a plan view of the spring metal sheet making contact with the outer terminal of the condenser; Fig. 7 is a fragmentary sectional view of a modification in which the conductive elements of the condenser comprise metallized coatings on the dielectric and the spring metal sheets merely serve to make contact with the condenser terminals; and Figs. 8

and 9 are plan views of modifications of the spring metal sheets.

Referring to the drawings, there is shown a condenser having circular mica disks l arranged between metal disks 2 and 3 preferably made of spring metal, such as spring brass. The mica and metal disks are stacked between mica end plates 4 and are compressed by a rivet 5. The rivet extends through a flange 6 on a terminal lug 1 so that when the rivet is headed over the terminal lug is fastened to the condenser. Washers 8 are arranged between the head of the rivet and the flange 6 and the adjacent end plates 4. Surrounding the condenser is an annular terminal 9 having, inwardly extending flanges I0 and II' engaging the outer faces of the end plates 4 and squeezing the end plates together. Preferably the terminal 9 is in the form of a cup with the flange Ill formed prior to assembly of the condenser. After the condenser is pressed into the cup, the rim of the r cup is headed over to form the other clamping flange H. The terminal construction is such that the condenser is securely clamped together at the center and at the periphery of the mica disks.

ill

The metal disks 2 have a central opening I! substantially larger than central openings i3 in the mica disks and have serrated outer edges l4 projecting beyond the periphery of the mica disks. The serrations are bent along lines i5 slightly beyond the periphery of the mica disks and extend angularly into engagement with the inner wall of the terminal 9. The outside diameter of the metal disks 2 is slightly greater than the inside diameter of the terminal 9 so that as the condenser is pressed into the outer ter-- minal the serrations are flexed inwardly sufficient to provide the desired contact pressure. Between the serrations are scallops l6 which normally extend within the periphery of the mica disks l. The construction is such that bending of the serrations i4 is confined to the part projecting beyond the periphery of the mica disks.

The metal disks 3 are of smaller diameter than the mica disks l and have at the center a portion I! countersunk so as to project through the central openings i 3 in the mica disks. At the lower end of the countersunk portion is an opening I 8 having a smaller diameter than the outside diameter of the rivet 5. The Sides of the countersunk portion are slit at 19 providing a series of spring fingers 20, each having a concave end 2| engaging the outer surface of the rivet. As the rivet is pressed through the condenser, the spring fingers 20 yield outwardly and provide the desired contact pressure. The slits l9 may result from cracks in the metal as the countersunk portion is formed, in which case the slits will not be regularly located as illustrated. The countersunk portion I! being located entirely within the openings l3 in the mica disks, there is no danger of injury of the mica as the rivet is pressed through the condenser.

In this construction the capacity of the condenser is determined by the overlapping area of the metal disks 2 and 3in other words, the area between the openings 12 in the disks 2 and the outside diameter of the metal disks 3. It will be noted that the clamping pressure holding the condenser together is primarily outside the active area of the metal disks. The flanges l0 and H squeeze the end plates together outside the metal disks 3. The clamping pressure from the center rivet extends only slightly beyond the inner edge of the opening l2 in the metal disks 2. This tends to reduce the effect of temperature on the condenser capacity.

The use of spring metal serrations makes the terminal contact substantially unaffected by tially in contact with the terminals tended to set away from the terminals under thermal expansion and contraction and to locally interrupt the contact between one or more of the foils and the terminals. The failure of the foil condensers is unpredictable. The use of spring metal is therefore a substantial improvement in that there is no failure of the condenser due to breaking of contact between the metal disks and the terminals.

In Fig. 7 is shown one element of a condenser having a disk 22 of mica or ceramic having metalh'zed coatings 23 and 24 on opposite faces. The coating 23 extends from a central opening 25 in the disk to a point short of the periphery of the disk. The coating 24 extends from the periphery of the disk to a point short of the central opening 25. This results in an annular area of overlap spaced from the central opening 25 and the periphery of the disks which comprises the active area of the condenser. It will be understood that a complete condenser usually comprises a stack of disks 22. On the metal coating 23 is arranged a disk 26 of spring brass having serrations 21 projecting angularly into the central opening 25 and arranged to contact a center rivet in the same manner as the spring fingers 20 in the previously described construction. On the opposite face of the disk 22 is a spring metal disk 28 contacting the metal coating 24 and having at its periphery serrations 29 extending angularly beyond the periphery of the disk 22 and arranged to contact a cup shaped terminal in the same manner as the serrations I4. In this construction the metal disks 26 and 28 are relied upon solely to make contact with the condenser terminals. The capacity of the condenser is determined by the overlapping area of the metal coatings 23 and 24. This construction can be used in both ceramic and mica condensers.

In Figs. 8 and 9 are shown spring metal disks which may be substituted for the disks shown in Figs. 4 and 6. The disk shown in Fig. 8 which is intended to make contact with a center rivet has at its center spring fingers 30 having their inner ends normally defining an opening smaller than the outside diameter of the rivet. The spring fingers are separated by scallops 3| which extend within the center opening in the dielectric disk, the diameter of which is indicated by arcuate lines 32. The disk may be preformed so that the spring fingers extend in the desired direction or the disk may be assembled flat and the pressure exerted by the rivet may be relied upon to bend the spring fingers out and produce the desired contact.

The disk shown in Fig. 9 has an outside diameter equal to or slightly smaller than the diameter of the dielectric disk and has spring fingers 33 projecting beyond the dielectric disk and making contact with the cup shaped terminal. The spring fingers 33 may be partially bent on lines 34 in the desired direction so as to make the assembly easier or may be assembled flat so that the entire bending of the spring fingers will take place as the condenser is pressed into the terminal.

Where all of the bending of the spring fingers takes place during the assembly of the terminal, there is an increase in the manufacturing loss due to cracking of the edges of the dielectric. The preforming of the spring fingers as illustrated in Figs. 3 to 6 is therefore preferable.

What we claim as new is:

1. A condenser comprising a stack of centrally apertured dielectric disks having metallized coatings on opposite faces, the coatings on each face of the sheets being confined to one face and not extending over tothe opposite face, interleaved centrally apertured spring metal sheets between and lying fiat on the coatings on the disks, alternate of the sheets extending short of the central aperture and having serrations overhanging the periphery of the disks, and intermediate of the metal sheets extending short of the periphery of the disks and having serrated edges extending within the central aperture, a cylindrical terminal receiving the stack and contacting the peripheral serrations, and a center terminal comprising a rivet extending through the central aperture and contacting the serrations therein.

2. In a condenser, a stack of centrally apertured dielectric disks having overlapping metallized coatings on opposite faces thereof and interleaved centrally apertured spring metal disks, the coatings on each face of the disks being confined to one face and not extending over to the opposite face, said disks lying flat against each other and the metal disks engaging said coatings, alternate of the metal disks extending short of the central opening and having fingers overhanging the periphery of an adjacent dielectric disk, intermediate of the metal disks extending short of the periphery and having portions projecting within the central openings of an adjacent dielectric disk, a cylindrical terminal surrounding the stack having side walls engaging said fingers, and a central terminal engaging the portions of the metal disks within the central openings of the dielectric disks.

BYRON B. MINNIUM. MARCIUS LEE CROOKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number I Name 7 Date 1,754,268 Dubilier Apr. 15, 1930 2,223,172 George Nov. 26, 1940 2,459,332 McCown Jan. 18, 1949 FOREIGN PATENTS Number Country Date 129,934 Great Britain July 24, 1919 518,127 Great Britain Feb. 19, 1940 688,417 Germany Feb. 20, 1940 

